Continuation of the Pediatric AIDS Clinical Trials Unit at St. Jude Children's Research Hospital and its subsites at the University of Tennessee and Vanderbilt University is proposed. New affiliations with Washington University in St. Louis and Meharry Medical College are proposed for the current project. The objective is to support the scientific agenda of the Coordinating and Research Operations Center (CORC) proposed by Dr. Spector et al. and the NIAID HIV/AIDS research agenda. The three host cities, Memphis and Nashville, TN and St. Louis, MO are located in Mid-America, within urban areas with high-density African-American populations. There has been an increase in new infections in this minority, especially among adolescents. All provide HIV - specific care for surrounding rural populations as well. Each of the three programs has significant experience in the management of HIV-infected infants, children, adolescents, and pregnant women. Linkages with Ryan White, Title IV programs in each city enhance the access of patients to clinical trials. The team of proposed PACTG sites includes well-established academic specialists in pediatric and adult infectious diseases, immunology, pharmacology, virology, fetal and maternal medicine, and vaccinology. The team of investigators is experienced in the design and conduct of multicenter clinical trials and has successfully participated in the PACTG since 1992, consistently ranked as excellent. Investigators from this site have contributed to advancing the scientific aims of the group and have served in key leadership positions. Vanderbilt and Washington Universities are sites of Adult ACTUs and provide the opportunity to collaborate with these units for aging-up adolescents and pregnant women. Vanderbilt University is the also the site of an HIV Vaccine Trials Unit. During the next five years we will continue to advance the scientific agenda of the PACTG through the enrollment of infants, children adolescents and pregnant women in PACTG protocols, participate in the development of new clinical trials and leadership of the PACTG, and provide linkages with collaboration networks, such as the Adolescent Trials Network, and basic scientists at our institutions.